Reduction gear assembly



Patented June 26, 1945 REDUCTION GEAR ASSEMBLY' Gary Gf Bluemink and James Holly vNelson, Racine, Wis., assignors to The Dumore Company, a corporation of Wisconsin Application July 24, 1942, Serial No. 452,212

(Cl. 'Z4-425) 2 Claims.

This invention relates to improvements in reduction gear assemblies and particularly to a reduction gearing for a small motor, such as may be used for example as a machine gun ammunition booster.

The general object of the invention is to provide a reduction gearing by means of which a large amount of torque is available using a comparatively small assembly and particularly one employing a fractional horse power electric motor. l

A contributory object is to provide equipment in which the driven gear in a worm and gear assembly is mounted to resist a large thrust and in which said gearhas bearings within the same to permit mounting it in a Small space.

A further object of the invention is to pro-l vide a reduction gear assembly in which the Work shaft projects at right angles to the armature shaft to provide free ends on which sprockets may be mounted. l

Various other objects and advantages will be apparent from the more detailed description which is hereinafter given of one embodiment of the invention.

In the drawing:

Fig. 1 is a central, sectional elevation through the reduction gear assembly with the motor armature shown in elevation;

Fig. 2 is a section on the line 2-2 of Fig. 1;

Fig. 3 is a top plan View, partly in section, of the reduction gearing without the motor;

Fig. 4 is an end view of the motor with the end plate removed;

Fig. 5 is an end elevation of a worm gear; and

Fig. 6 is a half section and half elevation of the same.

'The motor, indicated as a whole at Ill, comprises a length of cylindrical steel tubing Il closed by end plates I2 and I3 bolted thereto. The pole pieces I4, I4 comprise metal stampings riveted together and secured to said tubing Il by suitable screws. The coils or eld windings I5 surround the reduced portions of the pole pieces and may be readily assembled thereon before the pole pieces are secured in position. In this way interference between the coils in placing them in the slots is overcome and each coil ts the core of the pole closely, which is important as the space at the ends is limited. This construction makes it possible to reduce the outside diameter of the motor for a given armature, or, conversely, permits the use of a larger armature rthan usual as compared with the diameter of the motor housing.

The armature I6 is mounted on an armature shaft Il, the latter having a pinion I8 at one end which is preferably integral with the shaft, i. e., it may be formed by cutting teeth in the end thereof. Said pinion meshes with a gear I9 on an extension or neck on the worm 20 and also is preferably integral therewith although Shown as a separate element in Fig. 3.

In order to mount said worm in a small space longitudinally, a xed shaft 2| is provided which extends through a central bore in lthe worm, the latter being mounted on needle bearings 22 of conventional form, between it and said shaft. At the left hand end of said worm as viewed in Fig. 3, a ball bearing raceway 23 is provided having a thrust Washer 24 between the inner raceway and said worm to transmit the *very considerable thrust which develops. The outer racewayv is mounted in a bearing cup 25 positioned against a wall of the housing 26 which constitutes an integral extension of the end closure I2, bolted to the tube length Il, as shown in Fig. I. Said housing 26 (Fig. 2) has a removable cover plate 2I and gasket 28.

yThe Worm 20 meshes with a worm wheel 30 which is slidably mounted on the shaft 3l to a very limited extent and drives the same through a suitable clutch mechanism as follows:

Said Worm `wheel 30, as shown in Figs. 2 and 6, has an extenion or hub 32 thereon on Which is non-rotatably mounted a clutch disk 33 having the usual inclined teeth 34 which mesh with corresponding teeth on the yieldingly mounted clutch disk 35. Said yieldingly mounted disk has a plurality of openings which receive pins 36 mounted in a hub 3l which is fixed on the shaft 3I whereby rotation of said Worm wheel will drive said shaft in one direction through said cooperating clutch plates. Said plates are normally pressed together by' a helical spring 38 to maintain said clutch teeth in yielding engagement. The shaft 3| is mounted in suitable bearings 39 arranged intermediate the ends of said shaft and a thrust Washer 40 is positioned between vthe worm wheel and one of said bearings.

With the arrangement described above the ends of the shaft 3l project beyond the housing 26 in Which it is mounted, and sprockets 4I are mounted on each end. As shown in Fig. 2, these sprockets are spaced apart sufficiently to clear the cylindrical housing II. The space between the teeth on said sprockets are shaped to receive machine gun cartridges such as outlined at 42, the purpose of this embodiment of the invention being to serve as a machine gun ammunition booster to feed the flexible belt which contains said cartridges. The operator may pull said belt ahead when the motor is idle, by virtue of the clutch arrangement previously described. Each cartridge is considerably longer than the space between the sprockets 4I. The arrangement described provides the necessary clearance so the said cartridge cannot interfere with any pait of thehousingas will be v.understood from Fig. 1 where-the lower left hand end ofthe housing 2S is curved along an arc concentric with the axis of said sprockets.

It will be noted in Fig. 2 that'there is.- a elearance between the left hand sidecf the thrust washer lill and the adjacent :bearingr :which permits the spring 38 to maintainfthelf-slidable worm wheel 30 normally slightly to the-left of its desired position. When the motor is operate ing, one of the components of the thrust developed by the worm gear results in forcing said 'Worm .wheel a little .to .the right against the action fof said [spring ,3.8, therebyA aligning said wor/m wheel accurately with theworm in the mosteffectiveoperating position which .is a position shownin saidlgure. l

,'Ihereisalsoa clearance .between the` inside surface ,of the tube' I I .and ,the flange 43 which is formed on each of theend closures I2 and I3. Said ange has aplurality oflradalprojections or lands `INI thereon, shown in dotted lines in Fig.' 2, which projections are .formed when the parts Vare die cast and which very vaccurately Center the armature shaftrwith respect to said tube II.

. When the device is mounted on Va machine gun' where the space is limited and where in other fields .of service the available vspace ,is small, itis important Itoa,provvide `as compact a structure as A.possible without sacrificing effectiveness. The freduction gear assembly shown herein is very effective inasmuch as with a fractional horse power electric motor Xthe torque delivered in inch Lpounds is .practically double that which `would :begavailable usingsome ofthe standard constructions. shaft is supported betweeni'its ends is-also important .as it Ileaves said ends Ifreefor the-two sprockets -or other equivalent"V devices. `If Jthis shaft-were merely 'a continuation "of a main motor driven shaftyit `would not-be as lfeasible The :fact y that x the 'work l. An electric motor and gear assembly as a unitary structure comprising ya housing having a dividing wall providing two compartments, the walls of one compartment forming a motor casing, an armature shaft mounted in the opposite pend .walls of said compartment and projecting through said dividing wall, a pinion on the projecting end Within the other com- `partme'nt, .a Worm'having another gear compactly disposed at one end'thereof and meshing .with @said pinion, `said worm having a central borehavxed shaft mounted in the walls of said.

compartment andk passing through said bore, anti-friction 'bearings `between Lsaid shaft yand said iworm aand :positioned --Within *the longitudinal .limits .of fthe latter, Imeans Vrfor taking up the .thrust at "one end `of said worm, a shaft mounted, intermediate its ends in said'compartment walls-toleavefboth 'endsfree, Vand a worm wheel and fcooperatingclutc'h mounted on an intermediate part -of lsaid `shaft and meshing with said worm -to-drive'said shaft 'in one direction and *permit 4said "shaft to 'be rotated independently when said worm is idle.

2. A Vgear assembly comprising a fractional horsepowermotor'having 'acasing'with a detachable endwall, Yanarmatura'and a shaft therefor, a -gear housing of which `said 'end wall constitutes a'part, apinion on saidshaft, a Worm having gear teeth Vat 'one end thereof meshing with-said pinion, said 'wormvhavin'g a central :one hundred and fifty pounds, .and a 'shaft mounted in said housing interme'diateits ends, projectingthrough opposite Vwalls atboth ends, and driven Afrom said worm.

GARY "G: BLUEMINK JAMES'I-IOLLY NELSON. 

